drag-drop

The drag-drop signal is emitted on the drop site when
the user drops the data onto the widget. The signal handler must determine
whether the cursor position is in a drop zone or not. If it is not in a
drop zone, it returns false and no further processing
is necessary. Otherwise, the handler returns true.
In this case, the handler must ensure that
drop_finish() is called to let
the source know that the drop is done. The call to
drop_finish() can be done either
directly or in a
"drag-data-received" handler
which gets triggered by calling
get_data to receive
the data for one or more of the supported targets.